Robotics is an excellent educational tool. Underwater robots in particular are a most promising educational tool rich with learning experiences that students can gain while constructing them. The present paper offers a simple "recipe" for building a reliable underwater robot demonstrated through a case study.The advantage of the described recipe over existing educational robotics kits is that it combines being low-cost and reliable at the same time. We illustrate how adopting the proposed recipe can teach students that it is possible to develop successful sophisticated engineering projects from simple, cheap off-the-shelf components and using only low-resources technological tools if they carefully employ the different engineering concepts that they learnt through their different studies. In addition to that, the paper includes some important recommendations for instructors regarding how to use described recipe to teach students some important basic concepts and skills